Scalable web server cluster system using content-aware packet filtering

Abstract

Web server clusters are used to solve growing traffics of World Wide Web. Important issues of Web cluster system are selection of alternative request routing mechanism and construction of efficient architecture modeling. Content-aware request routing mechanism is a technique that routes incoming packets to target server from content information of HTTP request. Growing demands of WWW, the content-aware routing mechanism is more essential and used in many Web cluster systems. Virtual Web cluster system is a typical Web cluster architecture that does not use a front-end dispatcher and puts cluster servers on back-end and dispatcher on each server. As all cluster servers share one VIP address, the problems of the other systems (Cluster-based Web system and Distributed Web system) do not appear in this system. The virtual Web cluster system, however, cannot apply the content-aware routing mechanism. In this paper, we propose a new scalable and simple Web server cluster system based on modified virtual Web cluster system and content-aware routing mechanism. This system inherits advantages of the virtual Web cluster system and reduces the overheads obtained from TCP handoff mechanism. Moreover it can use various first-level routing policies at TCP connection and supports scalable and simple operations on persistent connection (HTTP 1.1). We design and implement this system using Linux Kernel modules. Experimental results of this system, user response time and throughput, demonstrates this system is more efficient than the other systems.